Where is calcium found
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Sources and Distribution of Calcium
Calcium in the Human Body
Abundance in Bones and Teeth
Calcium is the most abundant mineral in the human body, with approximately 99% of it stored in bones and teeth. This mineral is crucial for maintaining the rigidity and strength of the skeletal system 134. The remaining 1% to 2% of calcium is involved in various metabolic functions, including heart function, nerve transmission, and blood clotting 13.
Physiological Roles
Beyond its structural role, calcium is essential for several physiological processes. It plays a critical role in vascular contraction and dilation, muscle function, intracellular signaling, and hormonal secretion 7. The free, hydrated cation form of calcium, often referred to as "ionized calcium," is a key mediator in many metabolic and regulatory processes 8.
Calcium in the Environment
Abundance in Nature
Calcium is the fifth most abundant element in the biosphere, following iron, aluminum, silicon, and oxygen. It is a major component of limestone, marble, coral, pearls, seashells, and eggshells 2. Calcium salts exhibit intermediate solubility, allowing calcium to be found both in solid form (rocks) and in solution 2.
Presence in Water and Soil
Calcium is present in seawater at concentrations of approximately 10 mmol per liter, which is significantly higher than the calcium concentration in the extracellular fluid of higher vertebrates 2. Freshwater bodies that support abundant biota typically contain calcium concentrations ranging from 1 to 2 mmol per liter 2. In soils, calcium exists as an exchangeable cation in soil colloids and is readily taken up by plants 2.
Calcium in Plants
Nutritional Requirements
Calcium is an essential nutrient for plants, required for various structural roles in cell walls and membranes. It also acts as a counter-cation for inorganic and organic anions in the vacuole and serves as an intracellular messenger coordinating responses to developmental cues and environmental challenges 10. The calcium content in plants varies, with the highest concentrations typically found in leaves, followed by stems and roots, and the lowest in seeds 2.
Mechanisms of Calcium Transport
Recent research has focused on understanding the mechanisms of calcium transport across cellular membranes in plants, the origins and specificity of cytosolic calcium signals, and the cellular sensors that allow plant cells to respond to these signals 10.
Dietary Sources of Calcium
Food Sources
The primary dietary sources of calcium include milk and milk derivatives, green leafy vegetables, fruits, and legumes 9. The bioavailability of dietary calcium depends on various physiological and dietary factors, including age, physiological status, and vitamin D levels 9.
Supplements and Health Implications
Calcium supplements are commonly used to meet dietary needs, especially when dietary intake is insufficient. However, there is ongoing debate about the potential cardiovascular risks associated with calcium supplementation. While some studies suggest an increased risk of myocardial infarction, others find no consistent evidence linking calcium supplements to cardiovascular events 7.
Conclusion
Calcium is a vital mineral found abundantly in the human body, environment, and plants. It plays crucial roles in structural integrity, physiological processes, and metabolic functions. Understanding the sources and distribution of calcium can help in managing dietary intake and addressing health concerns related to calcium deficiency or excess.
Sources and full results
Most relevant research papers on this topic
Calcium
Adequate calcium intake is crucial for maintaining bone health, heart function, nerve transmission, and blood clotting, as well as reducing the risk of osteoporosis, colon polyps, colon cancer, calcium oxalate kidney stones, and hypertension and cholesterol.
Highly CitedCalcium, a Necessary Mineral for Proper Body Function
Calcium is a necessary mineral for proper body function, found in bone and teeth, and is found in various forms in foods and supplements.
Calcium metabolism and correcting calcium deficiencies.
This paper provides an overview of calcium requirements and dosing regimens, highlighting the importance of understanding absorptive mechanisms and factors affecting calcium metabolism to effectively correct calcium deficiencies.
Implementation of high resolution 43Ca solid state NMR spectroscopy: toward the elucidation of calcium sites in biological materials.
High resolution solid state NMR spectroscopy can reveal the electronic and coordination environment of calcium in biological materials, aiding in understanding biological processes.
Urinary calcium excretion in human beings.
Urinary calcium excretion in human beings is influenced by the solubility of calcium monohydrogen phosphate, which determines precipitation of calcium phosphates and the transformation to apatites, the principal skeletal mineral.
Highly CitedCalcium Supplements and Cardiovascular Disease Risk: What Do Clinicians and Patients Need to Know?
There is no consistent evidence linking calcium supplements to an increased risk of cardiovascular events, and further research is needed to confirm this conclusion.
Systematic Review
Rigorous JournalIonized calcium.
Ionized calcium testing is a useful and cost-effective method for assessing calcium homeostasis in patients, but other methods may be more practical and cost-effective for specific conditions.
Highly CitedCalcium, essential for health
Adequate dietary intake of calcium, phosphorus, and vitamin D is essential for maintaining bone health and cellular functions, and can help prevent osteoporosis, cancer, cardiovascular disease, and obesity.
Calcium in plants.
Calcium is essential for plant growth and development, and understanding its transport, signaling, and sensor systems is crucial for understanding and improving crop yields.
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